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Old May 28, 2013, 05:50 PM
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United States, MN, St Paul
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Help!
RCM 1/2a Basic Trainer

Hi,

I'm working on a RCM 1/2a basic trainer and am thoroughly confused ... (1st build FYI )

Plans - http://www.outerzone.co.uk/plan_details.asp?ID=3030

The concern I have is the landing gear mount. The plans call for 3/16 music wire but the mount as dictated by the plans is wide enough for twice that width. The instructions tell me to attach the gear with epoxy but that's going to take a lot of epoxy to fill that gap.

What do I do? Any help is appreciated!!!

thanks
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Old May 28, 2013, 06:10 PM
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United States, CA, Thousand Oaks
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Without having the plans in front of me, I suspect that design uses a two-piece landing gear, with the 3/32" music-wire legs overlapping each other in the fuselage bottom. This is the "torsion-bar" arrangement that was very popular for many years. The slot in the mounting block will be 3/16" wide and 3/32" deep, to allow the two individual legs to fit in the slot, where they will be retained by a pair of flat nylon straps and wood screws. I have the plans for the 1/2-A Basic Trainer someplace in my Pile-O-Stuff and I'll see if I can find them tonight. In the meantime, I hope this description helps.
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Old May 28, 2013, 06:12 PM
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OK, I just looked at the Outerzone link to the plan, and that's exactly what is called out. Just make two gear legs as shown on the plans, and you should be able to visualize how they are installed in the fuselage.
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Old May 28, 2013, 09:02 PM
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Yep, goes in like this image here. This is a pic of the bottom of a Hobbistar trainer and the landing gear fits in the same way.
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Old May 28, 2013, 09:04 PM
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Western KY
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Moeregaard's description is dead on. One gear leg sits in front of the second --- the only thing you must adjust for is where the short bend passes thru the bottom of the fuselage and where the internal supports are placed for the short bend.

The image posted by JohnsPop should really clear things up.
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Old May 29, 2013, 02:46 AM
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Ελλάδα, Ανατολική Μακεδονία Θράκη, Βιστωνίδα
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All article RCM 1/2a Basic Trainer for help.

More articles from magazine RCM here link

http://pulling-gz.blogspot.gr/
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Old May 29, 2013, 10:47 AM
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Ahhh now I get it!!! The thought that they would overlap each other never occurred to me

The plans call for a couple of 1/4 x 1/2 x 3/4 soft pine blocks to be epoxied to the top of the mount. From the picture that JohnsPop posted (thanks for that, I don't think I would have gotten it without the pic) it looks like I should drill mounting holes into these blocks. From what I understand the landing gear is usually the 1st part to fail. Are the blocks, with a hole drilled though, going to the solid enough to handle that kind of strain?

Also, I'm not finding "soft pine" at the LHS and as the plans call for 2 blocks 3/4 of an inch long, I'm not sure I'd want to pay for a 36" length if it was available. Is there something else I can use instead?
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Old May 29, 2013, 10:58 AM
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If you can't find soft pine, you can substitute spruce, basswood, or anything else that's harder than balsa.

The internal support blocks will be more than strong enough, since much of the landing loads will be absorbed through bending and torsional forces, with the support blocks reacting against these forces. Obviously, everything has its limits, but if you experience an "arrival" with enough force to break the support blocks loose, your airplane will have a lot of other problems as well. This landing-gear system has worked well on much heavier and faster models than yours, so I would just build it as designed.
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Old May 29, 2013, 11:03 PM
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Yeah, short of a wheel catching in a hole or something and giving it one heck of a *twist*, it's not going to break. You could probably go to Home Depot of somewhere and buy 1 foot of 1x2 (which is 3/4" thick") and saw off a piece to the size you need. A piece of poplar will probably work ok. You may even have some old scraps of 3/4" board laying around the house that would work. Depot also has a "scrap" bin where they sell busted off pieces and what not and if you explain to an associate what you're doing, he'll probably give you a little piece. I would have when I worked there.

On the ones I've done like that, after I drilled the holes straight into the block, I rounded the hole off toward the inside a bit to counter the bend in the wire so the wire wouldn't stick up. It lets the wire lay flush against your blocks. I've only done it with 40 and 60 sized gear though, so with smaller wire that may not be necessary.
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Old May 29, 2013, 11:13 PM
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You can get a 1x2x8' furring strip for a buck and change: http://www.homedepot.com/p/1-x-2-x-8...7#.UabRUsVQC0w

You'll probably have to trim, plane or sand the edge surface because on the cheap stuff, the edges are rounded off. Get it down flat and then just cut it to your 1/4 x 1/2 dimension. You can always find a use for the other 7'11" around your shop somewhere.
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Old May 30, 2013, 08:16 AM
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I have used that landing gear method in up to a .60 size plane and it never gave a me the slightest problem. Heavier parts a course.

Ken
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Old May 30, 2013, 09:37 AM
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It is a very simple and effective system. Tape the two legs together prior to bending them up as a single unit; you'll end up with identical pieces this way.
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Old May 30, 2013, 04:34 PM
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Ah, that's a good idea Moe. I wouldn't have thought of that and spent an hour trying to get them the same length! LOL
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Old May 31, 2013, 03:29 PM
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thanks for all the help guys!!! I believe I do have some scarp wood laying around that could work. ... and it's my favorite kind, ...already paid for

What do you guys use to bend your music wire? bench vice, vice grips, some special tool that I've never heard of, your teeth? Any tips or hazards I should be aware of?
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Old May 31, 2013, 04:11 PM
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I use a forge and anvil to bend, oh wait, wrong hobby...

For the most part I just use pliers. Bigger wire, bigger pliers. Sometimes I use a vise and hammer when the wire is big, like 1/8 and up. However, I never seem to make two landing gear the same.

George
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